1. Field of the Invention
The present invention relates to a communication system which allows remote mobile terminal equipment to call and interchange information with each other via a public switched telephone network, paging station, radio link controller, etc. The present invention is also concerned with terminal equipment applicable to such a comunication system.
2. Description of the Prior Art
In one of conventional mobile communication systems, a personal computer or similar information transmitting center calls radio terminal equipment having a receiving capability only via a public switched telephone network and a radio paging station and then sends desired information to the terminal equipment. The personal computer, for example, is installed in an office or similar facility while the terminal equipment is carried by a staffer belonging to the office. The staffer, therefore, can receive information from the office at any place outside the office. However, the problem with this system is that it is only the fixed center that can send information, i.e., such terminal equipment located outside the office cannot send information to another terminal equipment also located outside the office. More specifically, it is only the fixed center that can transmit call indication information.
Another conventional mobile communication system allows two remote radio terminal equipment, or mobile stations, to communicate with each other via a radio base station. In this kind of system, a radio base station is connected to a public switched telephone network via a central office. A mobile station intending to send information to a remote mobile station transmits an originating call signal. In response, the radio base station designates a particular communication channel and then checks the mobile station. When the communication channel is set up, the calling mobile station sends a dial number designating the mobile station to be called. The central office sends a calling signal to the called mobile station on the basis of the dial number. Then, the called station returns an answer signal, and the base station selects a communication channel. In this condition, the remote two mobile stations can start communication with each other over the designated communication channel. However, when the poerson expected to handle the called mobile station is absent or has suppressed the output of ringing, information cannot be delivered from the calling mobile station to the called mobile station despite the ringing from the calling station. Specifically, this conventional communication system does not take account of the fact that when the calling person sends information to a called mobile station, the called person may have left the called mobile station or intentionally switched off the mobile station or may not answer the call for one reason or another.